Blessings · The sky and nature
What is Kiddush Levana?
Kiddush Levana is the monthly blessing over the moon as it waxes — said standing, outdoors, and only when you can actually see the moon (Talmud, Sanhedrin 42a). Its window runs from about three days after the molad, the moon's renewal, until roughly the middle of the month.
The blessing that sanctifies the moon
Kiddush Levana — literally the sanctification of the moon — is the way the Jewish month lifts its head and blesses the sky. Once a month, as the moon returns and grows, we go outside, stand, look up, and bless the One who renews it. The Talmud (Sanhedrin 42a) treats this as a real encounter: you say it only when the moon is genuinely visible, not when cloud hides it from view.
The moon that shrinks to nothing and comes back has always been, for our people, a picture of a covenant that renews rather than ends. To bless it is to say that renewal out loud.
When and how
The custom is to say Kiddush Levana standing and in the open air, where you can see the moon. Its time is a window, not a single instant: from roughly three days after the molad — the moon's renewal, its monthly rebirth — until about the middle of the month, while the moon is still waxing and clearly seen. Communities differ on the earliest and latest moment; the source is Sanhedrin 42a, and your rabbi or community can tell you your local custom.
What to do
Early in the Jewish month, on a clear night, step outside and find the moon. Stand, look up, and say the blessing while it is visible. If a cloudy stretch keeps you waiting, that is normal — the window is generous, and you catch it on the next clear night. Don't let the month slip by unblessed; even stepping outside to look for the moon is the beginning of the mitzvah (commandment).
Source: Talmud, Sanhedrin 42a.
So the clear night doesn't pass you by, let Barkai (the blessings of the day; the sky and place tell you the moment) tell you when the moon is ready to be blessed.
Open Barkai